| In order to improve the survivability of submarines in deep water,acoustic stealth has become a trend of modern submarine development.The key technology of it fabricates pressure / sound absorption integration structure.The rubber sandwich structure composite material has the advantages of light weight,high strength,corrosion resistance,pressure absorption and sound absorption,which is a superior choice for submarine pressure / sound absorption structure in the future to replace the traditional anechoic tile structure(steel + sound stealth material),But the interface between the rubber and the fiber reinforced plastic(FRP)plane composite is weak,and the integrity of the sandwich structure composites under the action of force is easily damaged.Stitch reinforcement can effectively improve the stiffness of the sandwich structure.Avoiding the acoustic core compression caused by the decline in acoustic performance.The preparation of stitch reinforced rubber sandwich composites was studied in this paper.A new type of rubber sandwich composite was prepared by Vaccum Assisting Resin Transform Moulding(VARTM).The mechanical properties and acoustic properties of rubber sandwich composites under different stitch parameters were studied.The main contents are as follows:(1)Stitch structure of sandwich structure was designed,and the different design of stitching fiber reinforced rubber sandwich structure preform was fabricated by connecting the FRP composite plane and the rubber core material by continuous fiber stitch.(2)The influence of the stitch parameters on the compressibility of rubber sandwich composites was investigated.The results show that Compressibility of composites reinforced by suture-reinforced sandwich composites are obviously higher than those of conventional rubber sandwich materials.Compressibility increases with the decrease of the distance of the composite columns.Compressibility increases with the increase of the number of sutures.The effect of the number of stitches on the Compressibility is small.(3)The effect of suture parameters on the flexural properties of rubber sandwich was investigated.The results show that: the flexural rigidity of the composite reinforced by suture is obviously higher than that of the traditional rubber sandwich material,but the flexural failure load has no obvious change,The flexural stiffness increases with the decrease of the spacing of the composite columns;Stiffness ascends with the increase in the number of sutures,the effect of the number of stitched layers on the flexural performance is small.(4)The effects of suture parameters on the flatwise tensile properties of rubber sandwich were investigated.The results show that: The tensile properties of the composite reinforced by suture are significantly higher than those of the conventional rubber sandwich.The tensile strength increases with the decrease of the distance of the composite columns,the tensile strength increases slightly with the increase of the number of sutures,tensile strength with the number of suture layer increased slightly.(5)The underwater sound absorption performance of rubber sandwich was investigated.The results show that: the sound absorption coefficient of the rubber sandwich structure increases gradually with the increase of the acoustic frequency,the acoustic transmission coefficient gradually decreases and the reflection coefficient increases gradually;under normal hydraulic pressure,the acoustic performance of the reinforced sandwich structure sample the sound absorption coefficient of the unenhanced samples was decreased.The sound absorption performance of the unenhanced samples decreased obviously when the hydraulic pressure was increased to 2 MPa,while sound absorption performance of stitched sample decreased little. |
